Simplifying onchain data access with Sequence Indexer on SKALE

Onchain data is the foundation of every great web3 application. But for many developers, accessing that data is still a challenge. Most indexer solutions available are too slow, too limited, or too expensive to scale reliably.

Sequence Indexer and Indexer Gateway offer a better solution: fast, flexible, multichain access to structured onchain data.

Whether you’re a developer building a game, marketplace, or application on SKALE, Sequence provides the tools to build smarter and move faster.

SKALE is a multichain network of zero gas fee blockchains designed to support fast, scalable applications without compromising user experience. Its zero gas fees and instant finality ensure that tools like Sequence Indexer can deliver near-instant, cost-free data access at scale. This foundation enables seamless real-time updates and high-frequency queries, crucial for powering dynamic games, marketplaces, and AI-driven dApps.

Explore how the SKALE Builder developers can use Sequence Indexer and the Indexer Gateway to fetch onchain data in real time, trigger backend logic with webhooks, and power seamless user experiences, all with just a few lines of code.

One API. Instant results.

The Sequence Indexer simplifies the process of querying and filtering onchain data across multiple chains, including SKALE testnet and mainnet, using a single API.

With Sequence Indexer, developers can:

• Query native balances, NFTs, and ERC20 tokens
• Pull full transaction history for any wallet or contract
• Retrieve token metadata (image, name, collection, traits) directly in the response
• Filter by a variety of parameters such as block number, contract address, token ID, and more
• Make multichain queries in a single API call

No need to stitch together multiple APIs or decode raw contract data. Sequence Indexer ensures all responses include clean, enriched metadata out of the box.

Realtime web3 updates? done.

Web3 is evolving in real-time, and apps should too. Sequence supports WebSocket and webhook functionality, making it easy to listen for events and respond the moment something happens onchain.

Thanks to SKALE’s near-instant block finality, these real-time responses happen without delay, ensuring developers can deliver seamless, interactive user experiences powered by reliable onchain triggers.

With this feature, developers can:

• Subscribe to contract events or token transfers
• Trigger in-game rewards, UI changes, or backend updates
• React to NFT mints, balance changes, or milestone completions
• Access structured metadata and parsed event details

Setting up a webhook takes just a few steps. Developers select the contract and events, provide a webhook URL, and Sequence takes care of the rest.

Built into SKALE Builder

The Sequence Indexer is integrated directly into the SKALE Builder UI, allowing developers to test and run queries with zero setup. The sandbox experience includes pre-configured API calls, parameter editors, and testnet/mainnet toggling.

As part of SKALE’s Toolsday campaign, James Lawton, Head of Developer Relations at Sequence, recorded a demo showcasing how the Indexer works in practice.

In this walkthrough video, developers will learn how to:

• Select SKALE chains and switch between testnet and mainnet
• Query token balances and NFT metadata
• Showcase how our automatic metadata spam filter protection works to customize what tokens to receive in a response
• Setup webhooks with your contracts to respond to onchain contract events
• Run live API tests and inspect response payloads

The demo highlights how the Sequence Indexer returns complete query results in just 351ms, fast enough to support real-time gameplay and responsive frontend updates.

Developers can export working requests in TypeScript or raw formats to plug directly into their stack.

Scale securely and confidently with Indexer Gateway

When serving onchain data to users, infrastructure exposure can become a bottleneck. The Sequence Indexer Gateway enables scoped, secure API access, ideal for consumer apps, wallets, and dashboards.

With Indexer Gateway, developers can:

• Issue API keys with defined scopes and rate limits
• Restrict access to specific endpoints, contracts, or chains
• Serve data from a managed gateway layer
• Monitor, throttle, and manage usage at scale

This enables developers to define exactly who accesses onchain data, when, and how, without the overhead of managing servers or risking backend exposure.

Designed for speed: Developer-first architecture

Sequence, the all-in-one web3 development platform, designed its Indexer to help modern teams ship faster, without the burden of managing infrastructure or handling low-level complexity.

Out of the box, developers get:

• Token metadata included in every response
• Multichain queries with a single API call
• WebSocket support for real-time updates
• NFT and ERC20 pricing info coming soon
• Zero infrastructure to maintain, just plug in and build

For teams migrating from legacy providers like SimpleHash, Sequence offers backwards-compatible endpoints and dedicated support to ensure a smooth and hassle-free transition.

Onchain data doesn’t have to be hard. With Sequence, it’s ready to use and just one call away.

Start building with better onchain data

Whether you're minting NFTs, tracking player assets, or powering a marketplace, Sequence gives you the data layer you’ve been waiting for.

• Try Sequence Indexer in SKALE Builder
• Read the Sequence docs
• Talk to us about your project